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1�1 1 F1 1 1 i 11 11 1 project component. Both alternatives seek to maximize the availability of the existing sewage force mains in the vicinity of the project service area by making direct connections to these existing force mains. This minimizes the need for construction of additional new force mains as part of this project. Gravity Collection System/Conventional Pumping Station Alternative Please refer to "Exhibit A," included in this report, which shows a schematic layout of the recommended gravity collection system with conventional pumping stations. Spot elevations are shown on the exhibit along with system elevations at various manholes in order to determine the estimated depth of the collection system at various points. As can be seen on the exhibit, the system depths vary from a minimum of 3' to a maximum of approximately 8'. The gravity collection system will involve the construction of two conventional pumping stations and it is anticipated that each of these pumping stations can discharge directly into the existing 6" and 18" force mains passing by each of the proposed stations. In addition, two small duplex grinder pumping stations must be constructed at the east end of 14th Place and 14th Street as shown on the exhibit. Please note the Gravity Sanitary Sewer Typical Trench Section shown on Exhibit C." The proposed gravity sewer design has been laid out to maintain the minimum depth possible. Even so, it is anticipated that all gravity collection sewer must be constructed into or beneath the 1 to 21 foot layer of hard limestone which exists 1 to 2 feet below the existing ground surface. As shown by the Typical Trench Section, the removal of the existing limestone layer will require the actual removal of practically all of the existing street paved cartway. In addi- tion, the sewer contractor will install a 4" diameter service lateral from the sewer main to the street right-of-way line for service to each of the 375 anticipated connections. The construction of each 4" service lateral will require additional removal of the hard limestone layer. Since the existing dwelling units are close together, and a service lateral is to be installed for each dwelling unit, it is anticipated that the entire 70' right -of - I.